Ecosyste.ms: Awesome
An open API service indexing awesome lists of open source software.
https://github.com/cyberzhg/mos-6502-restricted-assembler
A 6502 assembler with restricted functions
https://github.com/cyberzhg/mos-6502-restricted-assembler
6502-assembler
Last synced: 23 days ago
JSON representation
A 6502 assembler with restricted functions
- Host: GitHub
- URL: https://github.com/cyberzhg/mos-6502-restricted-assembler
- Owner: CyberZHG
- License: mit
- Created: 2021-01-01T07:29:22.000Z (about 4 years ago)
- Default Branch: main
- Last Pushed: 2021-11-28T06:45:11.000Z (about 3 years ago)
- Last Synced: 2024-12-08T18:50:33.733Z (about 1 month ago)
- Topics: 6502-assembler
- Language: Python
- Homepage:
- Size: 192 KB
- Stars: 0
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# 6502 Restricted Assembler
[](https://github.com/CyberZHG/cpu-6502-restricted-assembler/actions/workflows/python-test.yml)
[](https://coveralls.io/github/CyberZHG/mos-6502-restricted-assembler?branch=main)
A 6502 assembler with restricted functions.
## Install
```bash
pip install mos-6502-restricted-assembler
```
## Usage
```python
from asm_6502 import Assembler
code = """
START ORG $0080
JMP START
"""
assembler = Assembler()
results = assembler.assemble(code, add_entry=False)
# Results will be `[(0x0080, [0x4C, 0x80, 0x00])]`
# 0x0080 is the offset of the codes, the following are the bytes generated by the assembler.
code = """
ORG $0080
JMP $abcd
"""
results = assembler.assemble(code)
# Results will be `[
# (0x0080, [0x4C, 0xcd, 0xab]),
# (0xFFFC, [0x80, 0x00]),
# ]`
# By default, the assembler will set to 0xFFFE/F the address of the first line that can be executed.
```
## Instructions
### List
Official:
| | | | | | | | | | | | | | |
|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|
| ADC | AND | ASL | BCC | BCS | BEQ | BIT | BMI | BNE | BPL | BRK | BVC | BVS | CLC |
| CLD | CLI | CLV | CMP | CPX | CPY | DEC | DEX | DEY | EOR | INC | INX | INY | JMP |
| JSR | LDA | LDX | LDY | LSR | NOP | ORA | PHA | PHP | PLA | PLP | ROL | ROR | RTI |
| RTS | SBC | SEC | SED | SEI | STA | STX | STY | TAX | TAY | TSX | TXA | TXS | TYA |
Undocumented:
| | | | | | | | | | | | | | |
|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|
| ANC | ARR | ASR | DCP | ISC | JAM | LAS | LAX | RLA | RRA | SAX | SBX | SHA | SHS |
| SHX | SHY | SLO | SRE | XAA | - | - | - | - | - | - | - | - | - |
### Pseudo
```
ORG $0080 ; The following codes will be generated from this offset
.BYTE $AB ; Set to the current address $0080 with a byte $AB
.WORD $ABCD ; Set to the current address $0081 with two bytes $CD and $AB
.END ; This is equivelent to JMP *
```
### Addressing
```
START ORG $0080
.WORD *+3
NOP ; Implied addressing
JMP (START) ; Indirect addressing
LDA #10 ; Load $0A into the accumulator
LDA #LO $ABCD ; Load $CD into the accumulator
LDA #HI $ABCD ; Load $AB into the accumulator
LDA $00 ; Load into accumulator from zero-page address $00
LDA $10,X ; Load into accumulator from zero-page address ($10 + X) % $0100
LDX $10,Y ; Load into X from zero-page address ($10 + Y) % $0100
LDA $ABCD ; Load into accumulator from address $ABCD
LDA $ABCD,X ; Load into accumulator from address $ABCD + X
LDA $ABCD,Y ; Load into accumulator from address $ABCD + Y
LDA ($40,X) ; Load into accumulator from the 2-byte address contained in ($40 + X) % $0100
LDA ($40),Y ; Load into accumulator from (the 2-byte address contained in $40) + Y
```
Special rules for zero-page addressing:
```
LDA $0010 ; This is not zero-page addressing as the input contains a word
LDA * ; This is not zero-page addressing no matter what the current code address is
LDA LABEL ; This is not zero-page addressing no matter where LABEL points to
LDA $FF+10-10 ; This is not zero-page addressing as the intermedidate result is greater than a byte
```